I can't comment on prime rib becuase I don't eat it, but I can comment on the tenderloins.
I've had a tenderloin at every WDW resturant that serves them (except the Brown Derby), and it's far from the best.
It's not bad, I'm not daying that, but it's not what I'd call world-class, excellent, or any other superlative.
HOWEVER, for the money, it's an excellent value.
We found service friendly and efficient.
The din from Chef Mickey's can be beyond distracting, and border on very annoying.
It's very kid/family friendly.
Anne